So, I have compressor surge and bpv flutter and I am wondering what the cause is.

I have had this for quite some time now.

I know people have the same AEM intake as I do and don't have the surge and flutter.

Are there any known cures for flutter and surge?

 

BOV spring is too heavy.

 

...
I have the stock spring in there.

 

I think it has something to do with the tune. I know I've heard of a lot of stock cars and especially GMS1 cars having flutter, and a tune fixed it. I know tunes have fixed flutter before.

 

Ok, Then we need my tuner Terminator2 to chime in...where are you Term?

I am wondering if my altiutide combined with the AEM intake have caused this? It only happens at light throttle or when reving the engine. I love the AEM intake so I don't wanna ditch it if it is not causeing the paroblem.

But I am custom tuned for the AEM.

 

There is a difference between compressor surge and bov flutter. BOV flutter happens when you have too heavy to a spring in the BOV, sometimes the BOV closes too/early/late. Surge is cause by your wheel spinning in the wrong direction. It will happen on full throttle on your way to redline. This is real compressor surge. Its dangerous.

 

I have the AEM Intake like you and mine flutters like crazy

 

When I had mine it did also. That honkin' silicone elbow sets up a resonant pulsation with the BPV.

Cold starts with the cat warm up mode were embarrassing. Wubwubwubwubwub

 

no surge here.... no silicone either though

 

surge doesnt happen when ur wheel spins in the wrong direction, that would need alot more air going back into the compresser to make it change direction, its caused simply by the air pressure not being released by the bov and going back into the compresser wheel which will slow it down, but probably not change its direction.

an examply, turn on a house fan and take and air compresser and blow air back into the blades, ull get the same flutter sound, fan will slow down but not reverse.

 

Ok, So if it simply happens when i am reving or at low throttle it is for sure BPV flutter and not dangerous? I have never had any strange noises at WOT.

Oh, and would the Forge BPV help or hurt?

I had extra vacuum hose and I tried the vacuum tank bypas but that made it worse.

I can live with it, if it does not damage the car.

 

Maybe I should have said air causing resistance to the compressor wheel.

DO you get a complete blow off... say letting off at 10+ PSI?

 

here is the wiki def:

"A compressor stall is a situation of abnormal airflow resulting from a stall of the aerofoils within the compressor. Stall is found in dynamic compressors, particularly axial compressors, as used in jet engines and turbochargers for reciprocating engines."

 

Humm, So is that what I have or is it BPV flutter.

 

If I totaly let off the throttle I always have a full blow off, but the vacuum at my altiutde is lower than the vacuum for you guys at lower altiutde.

 

I am at 4K feet. I had to experiment with different springs. I settled on the 8 PSI spring for my tial Q. Little to no flutter, and no surge. Also idle like butter on startup.

sounds like from all the reviews I read your flutter is from the intake.

 

I am at 5k feet, I have the stock BPV and spring, the AEM intake I know has had problems in the past but Terminator2 swears by it and my LTFT and STFT are spot on so I don't wanna change it cause then I will need a new tune. I am hoping that the Forge BPV with their green spring will solve this problem. But it is a 150$ gamble.

 

wrong. Compressor surge happens when throttle closes and has to do 100% with the extra air not exiting the system, Straight from Maximum Boost by Corky Bell

What is compressor surge, and how can it be countered?
Compressor surge is the rapid fluctuation of turbine speed caused by the
throttle's being closed under boost. Rapidly spinning air compressors (turbos)
can go unstuble briefly when this occurs. The fluctuating speed can be damaging
TO the turbo, and the accompanying noise is obnoxious. The condition can
be alleviated with a compressor bypass valve that opens as the throttle closes
and allows air exiting the turbo to vent back to the front This keeps the flow
up

 

[QUOTE=drewbroo;5347977]Maybe I should have said air causing resistance to the compressor wheel.


that would have made more sense. lol

 

Not sure why your car is fluttering. Mine did not once I changed the cam tables. Did PrincessTurbo ever load my cam changes into your car? It was the last tune file I sent him for your car.

 

Your fuel trims were off by only 2% to begin with. I hardly needed to touch them in the first place.

 

What do you think Term? Do I need to address the BPV flutter or compressor surge issue? If so, what would be the best approach?

 

Don't worry about it, it's a characteristic of this intake. The important thing is that it does not happen under any kind of high throttle load or high rpm.

 

id have to hear it to be positive, but i highly doubt youve got a surge issue. actual surge is a hugely dynamic event for the turbo to experience, the result is one(or more) massively loud "chirps" once youve heard it, you'll likely never forget.

it can happen from wheel over speed Vs cover size, ineffective BPV/BOV, ect. depending on vacuum loads you might have compressor choke as it makes a pretty surge like sound, but youd feel the power drop before this happend.

since your not screaming about one hell of a noise, i'll bet on BPV issues. the forge unit would do nicely if you want to replace the stocker.

have you inspected your bpv unit? a cut diaphragm, among about a million other things, can cause a flutter.

 

I plan on checking my BPV diaphram this weekend.